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July 24, 1956 s. c. ELLERBECK NONREVERSING COUNTERCONTROL. FOR DIVISION OPERATIONS 5 Sheets-Sheet 1 Filed Nov. 20 1951 K n... M WWW m1 N L N R w fi fl 1' m7 W m O M M 1 f WW A Z n M G U w I NM :3 M J, O

m O E July 24, 1956 G. c. ELLERBECK NONREVERSING COUNTERCONTROL FOR DIVISION OPERATIONS Sheets-Sheet 2 Filed Nov. 20, 1951 GRANT C. ELLERBECK INVENTOR.

AT TORNEY July 24, 1956 a. c. ELLERBECK NONREVERSING COUNTERCONTROL FOR DIVISION OPERATIONS Filed Nov. 20, 1951 5 Sheets-Sheet 3 GRANT c. ELLERBEC'K.

IN VEN TOR.

ATTORNEY July 24, 1956 G. c. ELLERBECK NONREVERSING COUNTERCONTROL FOR DIVISION OPERATIONS Filed Nov. 20, 1951 5 Sheets-Sheet 4 GRANT C. ELLERBECK.

INVENTOR.

AT TOP N E Y.

July 24, 1956 G. c. ELLERBECK NONREVERSING COUNTERCONTROL FOR DIVISION OPERATIONS Filed NOV. 20, 1951 5 Sheets-5heet 5 GRANT C. ELLERBECK INVENTOR ATTORNEY N ONREVERSIN G COUNTER CONTROL FOR 9 DIVISION OPERATIONS Grant C. Ellerbeck, San Leandro, Calif, assignor to Friden Calculating Machine Co., into, a corporation of California Application November 20, 1951, Serial No. 257,217

Claims. (Cl. 23 5--63) more particularly to an improved mechanism for performing automatic division.

For a conventional automatic division operation performed by a Thomas type machine, the revolutions counter mechanism is first conditioned for either a positive or a negative registration. Therefore, each subtraction of the divisor from the dividend, including the overdraft cycle, is registered in the counter either like or unlike the negative value entered in the accumulator. When an overdraft occurs, the machine is conditioned to add the divisor into the accumulator and correct the overdraft in one cycle. With the conditioning of the machine for this additive cycle the revolutions counter mechanism isalso reversed to correct the cyclic count of the machine and thereby register a true quotient in each ordinally shifted position of the carriage. The counter mechanism is then restrained as the plus-minus control for the accumulator is neutralized to permit a left shift of the carriage, thereby preventing registration of this cycle.

This invention relates to calculating machines, and

Immediately following the carriage shift the machine is again conditioned for subtraction and the counter mechanism is again restored to its initially adjusted position. it is extremely necessary, with a machine of this type operating at 500 R. P. M., that the time required to reverse the counter mechanism immediately following the overdraft cycle be limited to of a second or less. This rapid reversal of the counter mechanism is not desirable as there is often damage to the mechanism resultingfrom misalignment of certain parts. In my invention 1 have overcome the necessity of this sudden reversal of the revolutions counter mechanism by first locking the counter control in a preselected position for the duration of the division operation. Simultaneously, the counting mechanism is automatically controlled to prevent registration of the first subtract cycle, the overdraft correction cycle, and the shift cycle in each ordinal position of the carriage. Hence, only the subtract cycles, including the overdraft cycle, and excluding the first subtract cycle are counted.

It is an object of my invention to provide an improved revolutions counter control in an automatic division operation.

Another object of my invention is to provide a means for positively retaining the revolutions counter control mechanism in a preset position throughout an automatic division operation.

Another object of my invention is to provide a revolutions counter operation restraining means Which is controlled by the division program control mechanism.

Another object of my invention is to provide a calculating machine vwith a revolutions counter control mechanism whereby the necessity for changing the counter actuation from positive to negative, or negative to positive following the overdraft cycle in division is eliminated.

Anotherobject of my invention is to provide a calculating machinewith a revolutions counter mechanism wherein. only predetermined subtract cycles of an automatic division operation are registered.

nited States Patent 0 "ice Another object of my invention is to provide a calculating machine with a revolutions counter control mechanism for restraining actuation of the counter during a dividend aligning operation after automatic division has been initiated.

Further objects will be apparent from the following description of the invention as illustrated in the accompanying drawings in which:

Fig. 1 is a fragmentary longitudinal elevation of the rear portion of the machine.

Fig. 2 is a fragmentary elevational view of the counter actuator sign character determining mechanism.

Fig. 3 is a plan view of the counter actuator sign character determining mechanism taken on line 33 in Fig. 2.

Fig. 4 is an elevational view of a portion of the counter actuating mechanism.

Fig. 5 is an enlarged view of the revolutions counter control mechanism.

Fig. 6 is a detail of the counter blocking member.

Fig. 7 is an elevational view of the right side frame showing the revolutions counter control mechanism and a portion of the automatic division control mechanism.

Fig. 8 is a detail of the division program control mechanism.

Fig. 9 is an elevational view of the left side of the right side frame showing a portion of the division control mechanism. 7

Description of mechanism My invention is disclosed as embodied in a calculating machine of the type fully disclosed in the Patent No. 2,229,889, issued to Carl M. F. Friden, January 28, 1941, and the Patent No. 2,229,890, issued to Carl M. F. Friden, January 28, 1941, together with the improvements thereon illustrated in the Patent No. 2,294,111, issued to Carl M. F. Friden, August 25, 1942.

Generally, the machine comprises a frame and a carriage mounted for lateral shifting movement on the frame. The carriage mounts the registers of the machine comprising the accumulator and the revolutions counter, while the frame provides a support for the various mechanisms for controlling the entry of values in the registers. The frame includes the base (not shown) which supports casing 11 and has left and right side frame plates 12 and 14 (Figs. 1, 4, and 9) mounted thereon. A right side control plate 13 (Fig. 7) is mounted on the base to the right of frame plate 14, to which it is also rigidly secured by spacing members (not shown). The left side plate 12 and right side plate 14 are rigidly connected, as shown in Fig. 1, by various cross frame brackets 16, 17, 18 and 19, which serve to mount various mechanisms referred to hereinafter. Register carriage 22 (Fig. 1) is mounted on frame brackets 16 and 19, as by rollers 23, for endwise shifting movement laterally of the machine in either direction to various ordinal positions.

Drive actuating and selecting mechanisms The drive mechanism includes a source of power from which a single path of power is provided to a cyclic clutch control drive for all power-driven parts of the machine through the main drive shaft 32 (Figs. 1 and 7). This cyclic clutch mechanism is described fully in the construction disclosed in the Patent No. 2,229,889.

The clutch drives transverse shaft 32 to provide a cyclic unidirectional drive for the actuating means of the accumulator, the revolutions counter, and the shift mechanism.

Shaft 32 (Fig. 1) has bevel gear connections 41 with longitudinally extending accumulator actuating shafts 42 suitably journalled in cross brackets 18 and 20. Each shaft 42 carries a pair of toothed actuating drums 43 for a pair of adjacent orders of the machine, and for con. operation with the teeth of each drum 43, a pair of tentooth gears 44 are slidably and nonrotatably mounted on square shaft 46 which is suitably journalled in crossframe brackets 16, 17 and 18. As usual in this type of machine a shaft 46 is provided for each order of the machine. Gears 44 are selectively positioned with respect to the associated step teeth of the actuating drum in a conventional manner by means including a pair of differential spring-urged slides 47 associated with each ordinal row of numeral keys 48. Intermediate brackets 16 and 17, each shaft 46 is provided with a spool 51 slidably and nonrotatably mounted thereon and having opposite bevel gears 52 and 53 for cooperation with numeral wheel gear 54 of the associated order of the accumulator mechanism.

It will be understood that a value corresponding to the value of the depressed key can be entered either positively or negatively in the accumulator by selective positioning of plus-minus gears 52, 53 in the conventional manner under control of transversely extending strap 56 which is carried by a pair of similar arms 57 secured on shaft 58 suitably journalled in the side frames. Strap 56 and the series of plus-minus gears are urged to their centralized, or neutral, position shown in Fig. 1 by suitable centralizing means, not shown.

Accumulator mechanism The accumulator comprises a series of numeral wheels 61 (Fig. 1) each of which is carried at the upper end of a numeral wheel shaft 62 suitably journalled in carriage frame 63 and carrying a numeral wheel gear 54. Each shaft 62 has suitable spring-urged ball detents 64 to insure alignment of thedisplayed numeral on Wheel 61 with sight opening 65 in the carriage cover.

Any suitable conventional form of transfer mechanism may be associated with the accumulator and its actuating means. In the form selected for illustration the mechanism includes a transfer arm 66 (Fig. 1) mounted on carriage frame 63 in each order of the accumulator, a ten-tooth gear 67 on each of shafts 46 (except the lowest order), and a pair of transfer actuators 68 on each shaft 42. The above mechanism is of the type disclosed in the aforementioned patent to Friden No. 2,229,889.

Revolutions counter mechanism The revolutions counter which is also mounted in carriage 22 comprises numeral wheels 86 (Fig. 1) on respective shafts 87 which are journalled in carriage frame 63 and carriage rail 88 supported by suitable end plates 119. A numeral wheel 86 is provided for each ordinal position of the carriage and the displayed numeral of each wheel 86 is maintained in alignment with the associated sight opening by spring ball detent means 89. The number of actuations of the accumulator are registered in counter numeral wheels 86 (Fig. l) by an actuator of conventional construction indicated generally at 91 and driven from transverse shaft 32 by a wobbler or grooved cam 92 (Figs. 2 and 3) and a square motion cam 93 (Fig. 4).

The revolutions counter mechanism is fully disclosed in the patent to Friden No. 2,229,889, but will be described briefly here for a full understanding of the counter actuating mechanism.

The counter numeral wheels 86 are cyclically rotated for a positive or negative registration by the counter actuator 91 which is carried by shaft 94 (Figs. 1, 2 and 4) and operated to perform both a rotary oscillation and an axial reciprocation in timed relation during each cycle.

The means for controlling the axial reciprocation of the counter actuator 91 is of conventional construction. As seen in Fig. 2, the shaft 94 carries a grooved disk 95 which is engaged by a pin 96 secured to one end of a lever 97 mounted for rotation on an upright shaft 98 (Figs. 2 and 3). Lever 97 forms one-half of a forked 4 construction including a lower arm 99 secured at the lower end of sleeve 100 which is also secured to lever 97. Lever 97 and arm 99 carry respective pins 101 and 102 for engagement with respective cam grooves 103 and 104 of a wobbler cam 92 on drive shaft 32. Annular grooves 103 and 104 are of similar shape and size, and are angularly as well as axially displaced about the shaft, with the groove 104 being normally engaged by pin 102. Selective engagement of pins 101 and 102 with their respective grooves 103 and 104 is controlled by arm 105 secured to one end of a shaft 161 and having a pin 106 engaging between flanges 107 of a collar on sleeve 100. Thus, rotation of shaft 161 and arm 105 will determine a registration in the revolutions counter either like or unlike the registration in the accumulator dials 61.

The wobbler cam 92 rotates in the direction of the arrow in Fig. 2 so that with pin 102 engaged with the groove 104, the first part of the rotation produces no oscillation of lever 97 for 180 of the revolution. However, during the second 180 the lever 97 will be oscillated counter-clockwise as viewed in Fig. 3, held in this position for a few degrees and then returned to the position shown in Fig. 3. Conversely, if pin 101 is engaged with groove 103 initial movement of arm 97 will occur during the first 45 of the revolution of the wobbler cam 92 and this position will be maintained for approximately 90 when a return movement will occur followed by a dwell in the axial movement of lever 97 and the counter actuator 91. Thus each of cam grooves 103 and 104 controls an oscillation of the lever 97 and consequently an endwise reciprocation of the shaft 94, and therefore the counter actuator 91, with the reciprocation taking place in a timed relation of the cycle. This timed relation will be described later in connection with control of the oscillation of the counter actuator 91.

In its rotary oscillation, the actuator 91 is spring-driven clockwise (Figs. 1, 5 and 7) about the axis 94 of the actuator 91 so that such clockwise movement can be blocked. The counter actuator is driven cyclically in time with the actuating means for the accumulator.

The control for the oscillation of the counter actuator 91 comprises an arm 1418 (Fig. 4) secured on shaft 94 and carrying a pin 109 extending through an arcuate slot 110 in the left side frame 12, and engaged by the forked upper end of a cam follower, or bellcrank, 111 pivoted at 112 on left side frame 12. The cam follower 111 has an apertured portion 113 engaging cam 114 secured on shaft 32. Cam 114 is of a special construction to provide intermittent movement of the cam follower 111. The cam 114 has opposite portions 114a and 11% concentric with shaft 32. The portions 114a and 114b are of the same angular extent and are joined by similar opposed portions 114c, each of which is an arc struck about a center coincident with a junction of the opposite portion 1140 with portion 114a. In this fashion movement of the cam follower 111 will occur while it is engaged by the portions 114c and a dwell in its movement will occur while it is engaged by the portions 114a and 114b.

Fig. 4 illustrates the full-cycle position of the cam 114 and cam follower 111. Therefore, upon counter-clockwise movement of cam 114 the full-cycle position of the actuator element 111 will be maintained for about 55, after which the portions 114c become active, causing movement of the cam follower 111 in a clockwise direction (Fig. 4) so that and 108 and shaft 94 will be moved in a counter-clockwise direction. Thus, it will be seen that the transversely extending bail 124 (Figs. 1, 5, and 7) carried by arms 125, 126 disposed at opposite ends of, and pinned to, shaft 94, will be rocked clockwise as seen in Fig. 1, to tension springs 127 and thereby rock counter actuator 91 into active position. If the pin 102 (Figs. 2 and 3) is engaged with the cam groove 104 this movement to active position will take place before any reciprocatory movement of the actuator element. The initial reciprocato-ry movement will then occur during the dwell when the portions 114a and 114b are again active and before portions 114c serve to rock the counter actuator 91 to its inactive position seen in Fig. 1. After the cam 114 rocks the counter actuator 91 to its inactive position, the cam groove 104 then becomes active to restore the counter actuator 91 laterally to its full-cycle position.

if the pin 101 is engaged with the cam groove 103 the first movement of the counter actuator 91 is a reciprocatory displacement from the full-cycle position and this movement occurs before the cam 114 is rotated sufficiently counter-clockwise (Fig. 4) to bring its portions 1140 into active position. While the portions 1140 are then operative to rock the actuator 91 into its active position, the pin 101 is moving through an idle portion of the cam groove 103. The return movement of the counter actuator is performed by the cam groove 103 to register a value in the counter dials 86. Thereafter the cam portions 11 4c again become effective to restore the cam follower 111 and the actuator 91 to the full-cycle position shown in Fig. 4. For a more complete description of the revolutions counter mechanism, reference is to be had to Patent No. 2,229,889 issued to Carl M. F.

Friden, January 28, 1941.

As seen in Figs. 5, 6, and 7, the counter actuator 91 is provided with an arm 134 having an oifset car 135 at one end thereof. Means is provided for selectively preventing the spring-urged clockwise rocking movement of the counter actuator 91 to active position in the form of a counter blockout, or disabling slide, 136 suitably mounted for endwise sliding movement in the frame of the machine. Slide 136 has a finger 137 adapted for disposition beneath the ear 135' and is pivotally connected at 138 to a lever 139 pivotally mounted at 140 on frame plate 14 of the machine. Lever 139 (Fig. 5) is urged in a clockwise direction by spring 141 attached at its one end to an offset car 142 of lever 139 and at its other end to a stud (not shown) on the control plate 14. Slide 136 is moved to its active counter blocking position by means to be hereinafter described. When the finger 137 on the slide 136 is moved beneath the offset ear 135 (to the left of the position shown in Fig. 5), oscillation of shaft 94, arms 125, 126, and their common bail 124 (Fig. 1), causes the springs 127 to yield without rocking the actuators 91 to their active position.

Referring to Fig. 9 the control plate 13 carries certain conventional parts of the calculator including the plusminus slide 146, which is mounted for movement in either direction by means of arms 147 and 148. Ann 148 is pinned to shaft 58 (Figs. 1, 7, and 9) so that movement of plus-minus slide 146 will rock the shaft 58, arms 57, and transverse strap 56 to engage either of bevel gears 52 or 53 with accumulator gear 54 for a positive or negative registration, respectively, in the accumulator wheels 61. This movement of the plus-minus slide 146 also simultaneously controls the sign character registration of the revolutions counter and may be adjusted by any convenient means, e. g, by the usual plus-minus keys 149, 150 (Fig. 9) or by means of the division key 151.

In an automatic division operation, it is desirable to determine selectively the sign character of the value to be registered in the revolutions counter, i. e., Whether it be like or unlike the sign character of the value registered in the accumulator. For this purpose an arm 152 has a pin-arid-slot connection 153 with plus-minus slide 146 (Fig. 5) and is yieldably held against the pin 153 by means of a relatively strong spring 154. The opposite, or forked, en; of arm carries pins 155 and 156 for engagement with respective notches 157 and 158 in the counter setting member 159. Pin 155 is normally held in engagement with the notch 157 of the counter setting member 159 by a spring 160 (Fig. 5). This normal position of the pin 155, upon movement of the plus-minus 6 slide 146, conditions the counter actuating mechanism for a like registration in the counter numeral wheels 86. However, if pin 155 is raised out of engagement with its notch 157 by any suitable means such as the auxiliary control member 163 (Fig. 7) the pin 156 engages in the notch 158 of the counter setting member 159 to cause an unlike registration in the counter with respect to the accumulator wheels.

Counter setting member 159 is secured to one end of a shaft 161 journalled in frame plates 13, 14 and centralized in its full-cycle position by a detent 162. At its other end the shaft 161 carries an arm 105 and pin 106 (Figs. 2 and 3) to control engagement of the pin 101 with groove 103 or pin 102 with groove 104 of the cam 92. Therefore, as seen in Figs. 5 and 7, rearward movement of the plus-minus slide 146 will normally produce a positive registration in the accumulator wheels 61 and will tension the spring 154 to rotate the counter setting member 159 clockwise to effect a like registration in the counter wheels 86. Similarly, forward movement of plusminus slide 146 will produce a negative registration in the accumulator wheels and will rotate counter setting member 159 counter-clockwise for a like registration in the counter dials.

However, if the pin 156 has been moved into engagement with its notch 158 (Fig. 5) of the setting member 159 by any selective means, such as the counter-clockwise rotation of the auxiliary member 163 (Fig. 7) the registration in the counter dials 36 will be unlike that in the accumulator dials. That is, rearward movement of the slide 146 through pin 153 and relatively strong spring 15% rotates counter setting member 159 and shaft 161 counter-clockwise as viewed in Fig. 5, to cause a negative, or unlike, registration in the counter dials 86 while a positive registration occurs in the accumulator dials 61. Likewise forward movement of the plus-minus slide 146 will cause clockwise rotation of the counter setting memher 159 and shaft 161 with a resulting positive, or unlike, registration in the counter dials 86 while a negative value is registered in the accumulator wheels 61. This latter position of the arm 152 and pin 156 with respect to the counter setting member 159, that is, with pin 156 engaging. the notch 15-5, is particularly useful in the automatic division operation as will now be described.

Division mechanism The division mechanism is of the character disclosed in said patents to Friden Nos. 2,229,889 and 2,229,890 and includes a manually operable starting control key 151 (Fig. 9) which is mounted for endwise sliding movement on the auxiliary frame plate 13 by means of slots engaging studs 166 and spring-urged upwardly by a spring 167. At its lower end the key 151 is provided with a. surface for engagement with a roller 168 carried by slide 169 mounted for endwise sliding movement by respective slots engaging respective studs 170. Upon downward movement of division key 151 the slide 169 is moved rcarwardly, to the left as vi wed in Fig. 9, against the urgency of spring 171. A roller 172 carried by slide engages the end of a latch lever 173 (Fig. 7) which is pivoted at 174 on the right side of control plate 13 and is spring-urged to active position by spring 175. Latch L173 normally holds a spring-urged division setting member 176 in inoperative position. Member 176 is pivoted at 177 and urged in a counter-clockwise direction by spring 178. The setting member overlies a roller carried by a link 180 (Fig. 9) pivotally connected between a bellcranl; pivoted at and urged clockwise by spring 186 and a division control lever 187 pivotally mounted at 188 on an arm 189 pivoted at 190 to control plate 13. As fully explained in said patent, the position of arm 189 is controlled during division by the position of the eccentric cam 191.

A downward movement of link 180 (Fig. 9) operates through bellcrank 184 to move slide 192 to the left in 7 Fig. 9 to engage the clutch and close the motor contacts in a conventional manner.

A clockwise movement of the control lever, or bellcrank, 187 (Fig. 9) is utilized to set the machine for division as fully disclosed in said patents. For this purpose a notched end 193 of the lever 187 engages a pin 194 on the usual plus-minus control slide 146 to cam the slide to the right (Fig. 9) and thereby set the machine for a subtract operation. Latch pin 195 on bellcrank 187 is also engaged by a spring-urged latch lever 196 (Fig. 7) in a conventional manner to maintain the lever or bellcrank 187 in operative position throughout a division operation.

The division control lever 187 (Fig. 9) also carries a pin 200 underlying an arm 201 secured on a transverse shaft 202. Counter-clockwise rotation of shaft 202, upon clockwise rotation of bellcrank 187, is utilized to condition the overdraft responsive mechanism for use in division. This mechanism is fully described in the aforementioned patents and serves, when an overdraft occurs, to cause the shaft 203 (Figs. 7 and 9) and therefore the program gear 204 to be shifted axially for cooperative engagement with a mutilated gear 207 which is integral with idler gear 205. The idler gear 205 is meshed with a driving gear 206 secured to drive shaft 32. As will be explained hereinafter, three cycles of the driving gear 206 are required to rotate the axially translated shaft 203 and the eccentric cam 191 mounted thereon for one cycle to control the division operation.

Revolutions counter sign character control The various mechanical phases of an automatic division operation in a Thomas type machine include successive subtraction of the divisor from the highest order values of the dividend until an overdraft occurs. That is, the divisor is sequentially subtracted until the highest order value of the dividend becomes smaller than the divisor so that the ensuing subtract cycle causes 9s to be entered into the dials to the left of the dividend in the accumulator. For this series of subtractions the counter control setting member 159 (Figs. and 7) is adjusted with the initial movement of the plus-minus slide 146 for an unlike or like registration of each cycle of the machine depending upon the desire of the operator for either a positive or a complemental quotient. Subsequent movement of the plus-minus slide 146 for the overdraft correction cycle, in conventional operation, changes the sign character of the revolutions counter registration. The slide is then moved to its neutral, or inactive, position by the division program control mechanism. With the plus-minus slide in the latter position the carriage is automatically shifted to the left one ordinal position, after which this same slide is moved to its initial, or subtractive, position and the revolutions counter setting member is again conditioned for the preselected like or an unlike registration with respect to the accumulator. This same sequence of events continues until the carriage has been shifted to its extreme left-hand position.

Optionally, manually operable control means are provided whereby the operator can, if he desires, set the machine to provide for an unlike registration in the revolutions counter with respect to the accumulator during a division operation. Thus, it is convenient for the operator vto obtain true figure results in the quotient, by counting the subtraction cycles in a positive, or unlike,

manner.

For this purpose a manually operable counter control key 210 (Fig. 7) is provided in juxtaposed relation to the division key 151, so that the two keys can be easily operated together by a single manual depression, or so that the division lever can be operated alone if so desired. Counter control key 210 is mounted for endwise sliding movement on right control plate 13 by means of slots engaging studs 211 and is urged upwardly by a spring 212. At its lower end key 210 carries a roller 213 for camming engagement with one arm of a bellcrank 214 pivoted at 215 on control plate 13 and connected to lever 163 pivoted at 218 by means of a link 216. Therefore, depression of key 210 imparts a counterclockwise rotation to lever 163 and its foot 217, as viewed in Fig. 7, to lift the pin from notch 157 of counter setting member 159 (Fig. 5) and cause the pin 156 to engage the notch 158 of the member 159.

To obtain a complementary quotient the operator has but to depress the division control key 151 only, thereby permitting the pin 155 to remain in its normally engaged position with notch 157 of the counter control setting member 159 as shown in Figs. 5 and 7.

From the explanation given heretofore and more fully described in the afore-mentioned Patents Nos. 2,229,889 and 2,229,890, issued to Carl M. F. Friden, it will be understood that the division program control mechanism first causes the plus-minus slide 146 and therefore the plus-minus gears 52, 53 to be moved to a subtract position and then when an overdraft occurs, to an add position. Each such movement of the slide, in conventional machine operation, causes the revolutions counter control mechanism to also change the sign character registration in the counter dials 86.

The rapid conversion in the counter control mechanism during a division operation to change the counter registration from positive to negative or negative to positive, can be very troublesome. Assume, for example, that the machine has been conditioned for a division operation in which the operator desires a true or positive quotient, i. e., both keys 151 and 210 have been depressed simultaneously. The pin 156 (Figs. 5 and 7) has been raised into engagement with its notch 158 of the counter setting member 159 controlled by the plus-minus slide 146. In this position of the parts the initial, or leftward, movement of the slide 146 (Fig. 5) and clockwise rotation of the member 159 raises the pin 102 (Figs. 2 and 3) of the counter control mechanism into engagement with its cam groove 104 to cause an unlike registration in the counter wheels 86. On the overdraft cycle, when the division program control mechanism becomes effective to correct the overdraft, the pin 102 is immediately disengaged from its cam groove 104 and the pin 101 is lowered into its cam groove 103 to change the sign character of the counter registration. This sudden disengagement and engagement of the pins 102 and 101 respectively, becomes very diflicult when any part of the associated mechanism is out of adjustment. During this transition, i. e., in the interim when neither pin is engaged in its groove, any vibration of the parts with the machine in operation could cause misalignment of the pins and their grooves. Such misalignment may prevent operative engagement of the pin and groove, with a resultant error in registration, but eventually may deform the arms 97 or 90, or the pins 101 or 102 thereon, or may so gouge the cam grooves 103 or 104, that the counter mechanism may become inaccurate or the machine be broken.

In my invention I eliminate all of the foregoing difficulties by positively locking either pin 101 or 102 (Figs. 2 and 3) selectively, in its respective groove 103 or 104 during the entire division operation. I also show means for blocking registration in the revolutions counter dials 86 during the correction cycle, the shift cycle, and the first subtract cycle of the automatic division operation. This mechanism will now be described.

Counter control setting member 159 (Fig. 5) carries an arcuate member 222 pinned thereto, which member is provided with notches 220 and 221 for engagement by a pin 223 on an upwardly extending arm of bellcrank 224 pivoted at 225 to right side frame 13. The other arm of bell crank 224 underlies a pin 226 on division control lever 187 and is urged into engagement therewith by spring 160. Thus, upon the initiation of a division operation when the control lever 187 (Fig. 5) is rocked upwardly to move the slide 146 to the left, the pin 223 is urged into engagement with either notch 220 or 221 by spring 160. The setting; member 159 is therefore locked in its preselected clockwise or counter-clockwise adjusted position.

With the counter setting member locked against alternating movement during division it becomes necessary to prevent a registration in the revolutions counter for three cycles of operation, i. e., the first subtract cycle, the overdraft correction cycle, and the shift cycle. In order to render the counter actuating mechanism 91 inoperative during all but the selected subtract cycles of a division operation, the blocking, or disabling slide, 136 is moved to the left as viewed in Fig. 5 to position its car 137 under the offset ear 135 of the arm 134. This effective leftward movement of the slide 136 takes place at the outset of the division operation when the division setting lever 176 (Figs. 5 and 7) is rocked counterclockwise about its pivot 177. A cam follower 227 pivoted to the right side control plate 13 at 228 carries a roller 229 for cooperation with a cam 230 pinned to the program control shaft 203 and operating in cyclic relation with the mutilated gear 204. The cam follower, or actuator, arm 227 also carries a link 231 pivoted thereto at 232. At its other end the link 231 has a pinand-slot connection 233 with the division setting arm 176, with the slot in the link 231 being of sufiicient length to permit reciprocatory motion of the cam follower 227 and the link 231 under the control of a cam 230. The upper end of the cam follower arm 227 pivotally supports the front end of a link 234, which link, at its rear end, is pivoted at 235 to an arm 236 which is pinned to shaft 237. The shaft 237 is journalled in right side frame 14 and control plate 13 and has secured thereto a depending pin 238 for engagement with offset car 142 of the lever 139. The roller 229 on the actuator arm 227 and the blocking slide 136 are urged to their normally inactive positions shown in Fig. 5 by the relatively strong spring 141 acting through the offset ear 142, depending pin 23?, and the shaft 237. It can be seen that counterclockwise rotation of the division setting arm 176 will rock the shaft 237 counter-clockwise and therefore move the counter blocking or disabling slide 136 into active engagement with the offset ear 135 of the counter actuator 91.

It is desirable to latch the blocking slide 136 in its active position for the first cycle of the division operation, after which the slide may or may not come under the cyclic control of the cam 230. For this purpose, a latching bel-lcrank 244 is rotatably mounted on shaft 161 and is resiliently urged by means of a spring 245 into engagement with a pin 246 on an arm 247 which is likewise pivoted on shaft 161. The arm 247 has a slotted engagement with the pin 226 on division control lever 187 for rocking movement therewith. Upon initiation of a division operation, the rocking of the division initiating member 176, is effective (through link 231, follower arm 227, link 234 and arm 236) to rock shaft 237 and pin 238 thereon, which in turn rocks arm 139 (counterclockwise in Fig. 5) to move slide 136 forwardly to disable the counter actuator 91. Simultaneously the control lever 187 is moved upwardly to cause a pin 248 on one arm of the latching bellcrank 244 to be moved behind the shoulder 249 of the link 234 for one cycle of operation. At the conclusion of this first cycle of the machine operation a roller 250 on the idler gear 205 engages the cam face 251 of the latching bellcrank 244 to release the stud or pin 248 from its locking engagement with the link 234, thereby permitting restoration of the blocking slide 136 and its associated mechanism to its inactive position under the urgency of the spring 141.

The counter actuator 91 now becomes effective to cause registration in the revolutions counter dials 86 of each succeeding subtract cycle of the machine, including the overdraft cycle. If however, the divisor is greater than the highest significant values of the dividend an overdraft occurs in the first cycle. As outlined above, this cycle is not counted in the dials due to the fact that the division setting member 176 (Figs. 5 and 7) has been rocked counter-clockwise to rotate the shaft 237 and thereby mov e the blocking slide 136 into active engagement with the arm 134 of the counter actuator 91. When the overdraft occurs mechanism is provided to translate the shaft 203 axially and therefore the division program gear 204 and the cam 230. The cam 230 then becomes effective to continue restraint of the counter actuator for the subsequent three cycles and in cyclic relation to the release of the latch pin 243 by the roller 250.

conventionally, the program gear 204 is provided with three sets of three teeth each for cooperation with the mutilated gear 207 (Figs. 7 and 8) and the idler gear meshed with a gear 206 on the main drive shaft The first rotation of the shaft 203 adjusts the plus-minus slide 146 for an add cycle to correct the overdraft. The second 120 rotation of the shaft 203 neutralizes the plus-minus slide 146 and initiates a shift cycle to move the carriage one ordinal position to the left. The third 120 rotation of the shaft 203 returns the plus-minus slide 146 to its initial or subtract position, whereupon the divisor is again subtracted from the dividend. For a complete disclosure on the foregoing division program control mechanism reference is to be had to the afore-mentioned Patents Nos. 2,229,889 and 2,229,890.

With each cyclic rotation of the shaft 203 (Figs. 5 and 7) and the cam 230 secured thereto, the cam follower 227 and the shaft 237 is rocked to move the slide 136 to its active counter blocking position, where it is retained for three machine cycles. These three cycles have a distinct advantage in the use of my invention as they give the operator an excellent opportunity to transfer the quotient from the machine onto paper or into another device while the division operation progresses. As the machine completes one operation the operator can immediately begin the next. In division operations this saving of time could not be considered an incidental factor. In other calculating machines it is necessary for the operator to sit idly until the machine has completed the operation, for only then is he able to transfer quotients to his paper or into another mechanical device.

My invention is also very effective in calculating machines having division aligner mechanisms of the character fully described in the copending application to Anthony B. Machado et 211., S. N. 66,688, filed December 22, 1948, now Patent No. 2,653,765, issued September 29, 1953, which mechanism will now be described briefly.

Upon initiation of a division operation the aligner mechanism is operative to cause the accumulator carriage ,to be shifted ordinally to the right until a true overdraft .is effected. This true overdraft automatically conditions the machine for a left shift of the carriage and also sets the automatic division mechanism into operation. In each ordinally shifted position during the aligning phase, the divisor is subtracted once, during which subtractive cycle an overdraft condition is simulated by shifting shaft to the right, which places program gear 204 in the plane of gear 207. As heretofore explained, such shifting of shaft 203 places the machine under the control of the program gear 204 for three machine cycles, during which the keyboard, or divisor, value is added once to return the register, or dividend, value to its original value; the carriage shifted one order to the right; and the divisor again subtracted. Again, during the first subtractive cycle in. the higher order, an overdraft is simulated, thereby reinitiating the three-cycle program during which the simulated overdraft is again corrected, another ordinal shift of the carriage to the right is effected, and the machine is again set for subtraction. This sequence of events is repeated, that is, subtract, correction of the simulated overdraft, and shifting the carriage to the right until the highest significant figure of the dividend is shifted one ordinal position to the right of the highest significant figure in the divisor set in the keyboard. The divisor is then subtracted to create a true overdraft which disables the aligner mechanism and conditions the machine for the division operation.

The counter actuator 91 (Figs. 1, and 7) is rendered inoperative during the entire dividend aligning phase of the division operation since the depression of the key 151 (Fig. 9) causes the setting member 176 to rock the blocking slide 136 and its finger 137 under the offset ear 135 of the arm 134. The simulated overdraft occurring in the first cycle of the division operation, and in the first cycle of operation in each effective order of the accumulator causes rightward shifting of the shaft 203, thereby bringing the machine under the control of the mutilated gear 204. The ensuing rotation of the shaft 203 and the cam 230 maintains the counter actuator 91 effectively inoperative while the machine is under the control of the mutilated gear 204, i. e., during the correction of the simulated overdraft, the shift of the carriage to the right, and a single subtraction creating the next or following simulated overdraft.

Operation It is believed that the operation of the machine will be apparent from the foregoing description, but it will be reviewed briefly.

For the registration of a true or positive quotient in the revolutions counter dials 86 (Fig. l) the operator has but to depress the division key 151 and the counter control key 210 simultaneously. The downward movement of the key 210 (Fig. 7) moves the link 216 forwardly to rock the lever 163 and its extended foot 217 counter-clockwise to raise the pin 155 out of engagement with its notch 157 in the counter setting member 159 (Fig. 5 and engage the pin 156 with the notch 158 in the said member. The simultaneous depression of the key 151 cams the slide 169 to the left in Fig. 9 and through roller 172 (Fig. 7) trips the latch lever 173 to release the division setting member 176 for counterclockwise rotation by its strong spring 178. Upon release from the latch 173, the setting member 176 operates on roller 179 to rock the division control lever 187 into operative engagement with the plus-minus slide 146 to move it forwardly of the machine (Figs. 5 and 9) thereby engaging the subtraction bevel gears 53 with the accumulator gears 54 to cause a negative registration in the accumulator dials 61 (Fig. 1). This movement of the plus-minus slide 146 also rocks the counter setting member 159 in a clockwise direction where the notch 221 is engaged by the pin 223 under the urgency of spring 160. Such engagement positively locks the counter setting member 159 against further adjustment throughout the entire division operation. As the division control lever 187 is rocked (clockwise in Fig. 9, counter-clockwise in Figs. 5 and 7), the pin 226 rocks the arm 247 and therefore the latching bellcrank 244 counter-clockwise about the common pivot 161 through the spring 245.

As seen in Figs. 5 and 7, release of the division setting lever 176 rocks the actuator arm 227 counter-clockwise through link 231 to move the link 234 to the left as viewed in Fig. 7, where the pin 248 on latching bellcrank 244 engages the shoulder 249 of the link 234. It will be recalled that such movement of the link 234 rocks the shaft 237 to move the counter disabling slide 136 to its effective position, where it is latched by the bellcrank 24-4 for at least one cycle of operation.

In the first subtract cycle immediately following the initiation of the operation, a roller 252 (Fig. 7) secured to gear 206 engages the cam face 253 to relatch the division setting member 176. At the conclusion of this same first subtract cycle the roller 250 on the gear 205 engages the cam face 251 of the latching bellcrank 244 to release the pin 248 from the shoulder 249 of the link 234. The link 234 and blocking slide 136 are therefore urged to their normally inactive positions by the spring 141. The ensuing subtract cycles, including the overdraft cycle, are registered in the revolutions counter numeral wheels 86. When the overdraft occurs, the transverse shaft 203 is moved axially to align the mutilated division program gear 204 with the mutilated driving gear 207, the axial shifting occurring immediately prior to the time the leadin tooth on drive gear 207 could engage the first tooth on gear 203, i. e., immediately before the full cycle position of the parts shown in Fig. 8. In the last few degrees of this cycle of the drive shaft 32, the mutilated program gear 204 and cam 230 will be rotated about 60 degrees, to a position intermediate the subtractive position and the additive position of control gate 56. This will be sufficient for cam 230 to rock the follower arm 227 to the full extent of its throw-the movement of gate 56 to the additive position actually occurring in the first few degrees of the first cycle following the overdraft (the additive corrective cycle) and before a digitation phase of that cycle. Similarly, at the end of this corrective cycle the teeth of driving gear 207 again engage the teeth of gear 204 and initiate the further rotation of shaft 203 to move the control bellcrank 187 toward its intermediate position, although the position is not reached until after the start of the second cycle. Just before the end of the shift cycle (the second cycle following the overdraft) the gear 207 starts to rotate program gear 204 and shaft 203 towards their subtractive position shown in these figuresthe angular movement not being completed until after the start of the third cycle, but before the digitation phase of the third cycle. It is thus obvious that the cam 230 holds the power arm 227 in its forward, or counter blocking, position from the end of the cycle in which the overdraft occurs until after the first subtractive cycle has begun in the following order. The latch 244 will be operated idly at the end of the overdrafting cycle and in the first two cycles immediately following, for the cam 230 holds the counter blockout in its effective position during these cycles. The cam 230 is still effective, at the start of the first subtractive cycle in the adjacent order to hold the counter blockout slide at in its locking position-the cam 230 then being approximately 60 degrees from the full cycle position shown in Figs. 5 and 7. As the cam returns to the full cycle position shown, in this first subtractive cycle in the succeeding order, the link 234 is latched. in its forward, or counter blocking, position by means of the latch arm 244 and its pin 248, and is not released until after the counting operation in that cycle is completed. Thus the counter blockout is held in blocking position in the first subtractive cycle in each order and is not released until the first cycle is nearly completed, when the roller 250 engages the cam face 251 of the latch. As soon as the latch is released the spring 141 rocks counter control arm 139, pulling the locking slide to its retracted, or unblocking, position.

In a conventional machine for performing an automatic division operation, and when, for example, a true quotient is desired, leftward movement of the plus-minus slide 146 (Fig. 5) conditions the machine for substraction in the accumulator and adjusts the counter setting mechanism for an unlike, or positive, registration in the dials 86. When the overdraft occurs the division program control gear 204 with the cam 191 causes the plus-minus slide 146 (Figs. 7 and 9) to be moved rearwardly to correct the overdraft. At the same time the slide 146 adjusts the counter control setting member 159 for negative registration in the counter wheels 86. The carriage is then shifted one ordinal position to the left and the plusminus slide is again set for substraction. In my invention the counter setting member 159 is positioned at the outset of a division operation for unlike registration and locked positively in that condition. Thus, when the plus-minus 13 slide 146 is moved rearwardly to correct the overdraft the spring 154 yields to permit the pin 153 to move freely in the slot of the adjusting arm 152. For a better understanding of the foregoing operation, reference is to be had to the following schedule using a dividend of 303 and a divisor of 1.

Accumulator Operation Oounter, Old Counter, New

Method Method 1 Subtract 1 Add 00303 Shift 0 0 0 0 0 0 0 0 1 Subtract 1 Subtract 1 Subtract 1 Subtract 1 Add 00003 Shift 0 3 0 0 0 3 0 0 l Subtract Add 00003 Shift 0 3 0 0 0 3 0 0 1 Subtract l Subtract 1 Subtract 1 Subtract 1 Add *Counter reversed.

For a like registration in the revolutions counter dials 86, the key 151 alone is depressed. The pin 155 remains in its notch 157 or its normal position as shown in Fig. 5. Therefore, when the division control lever 187 is moved upwardly to move the plus-minus slide 146 to the left, the counter control setting member 159 is rocked counter-clockwise to align the notch 220 for engagement by the pin 223, thereby locking the member 159 against further adjustment for the duration of the division operation.

When the automatic division operation has concluded, the latch member 196 (Fig. 7) is released in a well known manner and the control lever 187 is permitted to return to its inactive position by spring 186 (Fig. 9). The clockwise rotation of the lever 187 (Fig. therefor releases the latching bellcrank 224 and its pin 223 from the actively engaged slot 220 or 221 so that the counter setting member 159 is free to return to its normal position. At the conclusion of the operation when the cam 230 is in its full-cycle position, as seen in Fig. 5, the counter restraining slide 136 is moved to its normally ineffective position by spring 141.

I claim:

1. In a cyclic calculating machine having a dividend factor receiving means, a divisor factor receiving means, shifting means for ordinally shifting one of said factor receiving means relative to the other, reversible means for causing entry of a value set in the divisor factor receiving means into the dividend factor receiving means additively of subtractively, an automatic division mechanism including means for controlling a multicyclic operation for each order, means for sensing an overdraft and means operated by said sensing means for reversing the reversible means for a single corrective cycle, operating the shifting means and again initiating operation in the shifted posi tion, revolutions counter wheels for registering the cycles of operation caused by said reversible means, a revolutions counter actuator, and a counter setting member including an adjusting means for said counter setting member operative in an automatic division operation to control the sign character of the quotient, a locking means for retaining said counter setting member in a preselected sign character control position for the entire duration of the division operation, positionable means for blocking operation of said actuator, and means controlled by said division mechanism for moving said positionable means to its blocking position during the first cycle in each order, during each corrective cycle, and during each ordinal shifting operation.

2. In a calculating machine having an ordinally shiftable accumulator in which a dividend may be registered, means for shifting said accumulator, a selection mechanism in which a divisor may be entered, digitation means for transmitting the value in the selection mechanism to the accumulator additively or subtractively, an automatic division mechanism for controlling operation of said digitation means and said shifting means in a program including an additive cycle, an ordinal shift of the accumulator, and initiation of repeated subtractive cycles, means responsive to an overdraft in said accumulator for initiating operation of said division mechanism, a revolutions counter register, and a resiliently operated actuator for said register operative additively or substratetively, a counter-control mechanism comprising a settable member positionable to control operation of said actuator for additive or subtractive registration, means for blocking operation of said actuator, and means operable by said division mechanism for operating said blocking means during said additive cycles, said ordinal shift cycles and the first of each of said repeated subtraction cycles.

3. In a calculating machine having an accumulator; digitating means for entering values into said accumulator additively or subtractively; means for shifting said accumulator with respect to said digitating means; a revolutions counter; a counter actuating means for said revolutions counter operative additively or subtractively; a restraining means for suppressing a count in said revolutions counter; means responsive to an overdraft in said accumulator; and an automatic division mechanism including a division control member for initiating a repeated subtractive operation of said digitating means and means operated by said overdraft responsive means for controlling said digitation means and said shifting means to sequentially correct the overdraft, shift the accumulator one ordinal position and reinitiate a repeated subtraction operation; means for adjusting said counter actuating means for additive or subtractive registration in said revolutions counter; a division setting member for enabling said division control member and initiating a division operation; a locking means operated by said division control member to retain said counter actuating means in an adjusted position; means operated by said division setting member for enabling said restraining means; a latch means conditioned by said division control member for engagement with said last-mentioned means to latch said restraining means in an operative position; a cyclically operated latch releasing means for releasing said latch means; mechanism rendered operative by said overdraft responsive means for operating said restraining means for plural cycles of operation during the correction, shift, and first subtractive cycles of each ordinal operation; and means operated by the division control member to release said locking means and to render said latch means inoperative at the conclusion of a division operation.

4. In a machine of the character described having an accumulator, a value indexing means, a digitation means for transmitting a value determined by said value indexing means into said accumulator positively or negatively, a revolutions counter, a revolutions counter actuator for causing registration of a positive or a negative value in the revolutions counter, a cam means for controlling said counter actuator with a positive or negative motion, a positionable member operable by said cam means for operating said actuator, a sign character control mechanism including a counter setting member for moving said positionable member into a positive or negative engagement with said cam means, means for ordinally shifting said accumulator, and a division mechanism for controlling operation of said digitation means and said shifting means in a program to an overdraft, an additive corrective cycle, an ordinal shift of the accumulator and reinitiation of successive subtractive cycles in the adjacent order a latch means rendered operative by said division mechanism for retaining said positionable member engaged, a blocking means rendered effective by said division mechanism for disabling said counter actuator during predetermined cycles of the machine, and a cyclically controlled latching means operative to maintain said blocking means effective to prevent a registration in the revolutions counter for said predetermined cycles of the machine.

5. In a machine of the character described having a shiftable accumulator in which a dividend may be set, means for shifting said accumulator, a selection mechanism, an actuating means for causing the entry of values determined by the selection mechanism into said accumulator additively or subtractively, an automatic division mechanism for controlling operation of said actuating means and said shifting means to divide a value in the accumulator by a value in the selection mechanism, a revolutions counter for registering a quotient, an actuator for the said revolutions counter, a positionable member operative to control the sign character actuation of said actuator for a positive or complementary quotient, and means for positioning said positionable member, the combination which comprises a counter locking member operated by the division mechanism to lock the positionable member in either adjusted position, a counter actuator disabling means, means associated with said division mechanism and operable thereby to render the counter actuator disabling means effective to suppress a count in the revolutions counter in all cycles of machine operation except the second and succeeding subtractive cycles of the digitation means and to disable said blocking means for the said second and succeeding subtractive cycles.

6. In a calculating machine having a division mechanism, a division initiating means, a revolutions counter, a revolutions counter actuator, a shiftable carriage, accumulator dials in said shiftable carriage, a selection mechanism, an actuating means for causing the entry of values set in said selection mechanism into said acin an adjusted positive or negative registering position,

means operable by said division initiating means for disabling said revolutions counter actuator, a latching means enabled by said division mechanism to hold said disabling means in operated position, a cam member associated with said division program control mechanism and operable' in response to said overdraft responsive means to move and hold said disabling means in operated position for a plurality of successive cycles, and cyclically operable means for disengaging said latching means.

7. In a calculating machine having an accumulator in which a dividend may be registered, a selection mechanism in which the divisor may be entered, a digitating means operative to transmit values in the selection mechanism into the accumulator additively or subtractively, means for shifting said accumulator, an automatic division mechanism for controlling operation of the digitating means and the shifting means, means responsive to an overdraft in said accumulator for controlling operation of said division mechanism, an initiating member for initiating a division operation, a revolutions counter register, a counter actuator for said counter register operative in a like or unlike manner with respect to said accumulator, and means for conditioning said actuator for either like or unlike operation, the combination comprising a locking means for said revolutions counter actuator whereby only the registration of a preselected sign character is permitted, means for restraining operation of said actuator, means operated by said initiating member for operating said restraining means for a single cycle of machine operation, and a cam means operated by said overdraft responsive means to operate said restraining means for three successive cycles of machine operation.

8. In a cyclically operable calculating machine having an ordinally arranged register in which a dividend may be set, an indexing means in which a divisor may be set, an ordinally arranged digitating means operative to enter a value set in said indexing means into said register additively or subtractively, means for shifting the relative ordinal positions of the register and the digitating means, an automatic division programming mechanism operative to control cycles of operation of said digiting means and said shifting means to divide a dividend value in said register by a divisor value in said indexing means, revoluticns counter wheels for registering a quotient, and a reversible revolutions counter actuator for additive or subtractive operation of said counter wheels, the combination which comprises disabling means for preventing operation of said actuator, a manually controlled adjusting means for setting the actuator for additive or subtractive operation, means for maintaining said actuator in either of its adjusted positions, and means controlled by said division programming mechanism for operating said disabling means during predetermined cycles of operation in each ordinal series of operations.

9. In a calculating machine having a register in which a dividend may be set; a selection mechanism in which a divisor may be set; an actuating means for transmitting values from the selection mechanism into the register additively or subtractively, means for shifting the register; an automatic division programming mechanism including means for operating the actuating means to continuously subtract the divisor from said dividend to an overdraft, then initiating an additive corrective cycle of the actuating means in which the divisor is restored to the dividend, and then operating the shifting means to shift the register one order; revolutions counter wheels for registering a quotient; and a reversible revolutions counter actuator for operating said counter wheels additively or subtractively; the combination which comprises disabling means for preventing operation of said actuator; means for selectively setting the actuator for additive or subtractive operation; means for retaining said actuator in its adjusted position throughout a division operation; and means controlled by said division programming mechanism for operating said disabling means during the corrective additive cycle, the shifting cycle, and the first subtractive cycle in any order.

10. In a calculating machine having a register in which a dividend may be set, means for shifting said register, an indexing means in which a divisor may be set, a digitating means operative to enter a value set in said indexing means into said register additively or subtractively, an automatic division programming mechanism operative to control the digitating means for multicyclic subtraction and single cycle addition and the shifting means to divide the dividend value in said register by a divisor value in said indexing means, revolutions counter wheels for registering a quotient, and a reversible revolutions counter actuator for additive or subtractive operation of said counter wheels, the combination which comprises a counter-control means for enabling or disabling operation of said actuator, an adjusting means for setting the actuator for additive or subtractive operation, and means controlled by said division programming mechanism for operating said counter-control means for enabling operation of said actuator in the second and each succeeding subtractive operation of the digitating means and for disabling said actuator in the other cycles of division operation.

References Cited in the file of this patent UNITED STATES PATENTS Laiho Nov. 15, Hilder May 30, Landsiedel Sept. 9, Britten Oct. 28, Machado Jan. 2, Friden Oct. 30, Boyden Ian. 15, Avery Jan. 15, Friden et al. July 2, Moody Nov. 16,

Fleming Mar. 17, 

